When Andrew Garfield bailed out of a scheduled appearance at the Oscars on Sunday night, Chris Evans was called to fill in. But the eleventh-hour switch of Spider-Man for Captain America during a tribute to superheroes has led to talk -- vigorously denied by those involved -- that Garfield pitched a hissy fit and disappointed a 5-year-old leukemia survivor.

The actor was set to introduce adorable Miles Scott as "the world's next superhero." Scott, better known as the adorable Batkid who saved San Francisco-turned-Gotham last November in a touching, Make-a-Wish-coordinated event, rehearsed his part on Saturday, decked out in a snazzy tux.

"The Academy was going to make [Miles] an official superhero during the Oscar ceremony," a source tells Page Six. "But, in the middle of the dress rehearsal, Garfield decided he didn't like his lines. Garfield refused to go by the script. He came up with his own lines. The producers felt that Garfield's [rewrites] were not appropriate. Garfield had a tantrum. He stormed off. Miles and his family, who were at the rehearsal, were devastated."

The Post's spy claims Garfield was "such a spoiled brat that he didn't even want to be a presenter." But was the actor to blame for the doubtlessly heartwarming bit being tossed out? The Wrap reports that he found the initial script "exploitative" and rewrote it, to the producers' chagrin, but later agreed to do the segment as written. Soon, the decision was made to chop the entire segment.

But the story doesn't end there.

After being cut from the ceremony, Miles and his family received an all-expenses paid trip to Disneyland for their trouble, along with a personal visit from Peter Parker.

"Andrew Garfield understood that his segment had to be omitted, and he drove to Disneyland on Monday to spend time with … Miles and his family," explained an Academy spokesman. "Due to the nature of a live show, hard decisions sometimes must be made, which require the Academy to cut segments due to the logistics of production."

Andrew, who has a reputation for being kind to his young fans, even held a personal Oscars ceremony -- complete with tuxes -- for Miles in the tyke's hotel room at Disneyland. See the cute pic here.

The fact that Garfield trekked to the Happiest Place on Earth so as not to disappoint a kid he doesn't know should go a long way toward putting the Page Six story to rest. And his reps have released a statement to ensure it's completely quashed.

"In full collaboration with the Academy and the show writer, Andrew prepared a segment for the Oscars to honor Miles Scott as the true hero that he is," says his camp. "As some point overnight on Saturday / Sunday morning, it was decided by those running the show that the segment didn't work in the ceremony. They decided to pull it -- Andrew and Miles were equally upset. The producers arranged for Miles and his family to visit Disneyland on Monday, and Andrew drove down to visit them and to bring Miles a personal gift."

Concludes the statement, "Andrew did the right thing for Batkid and anyone saying otherwise is flat out lying."

Miles, meanwhile, got back to the business of being a kid: On Thursday, he pulled out one of his two loose front teeth.

"He was hanging on to them so he could wear them with his tux," says his mom.